We shall use three well-defined but interrelated approaches to study postnatal differentiation of the eye in the cat. 1.) Electrophysiological studies will be done using single unit, isolated retina and intracellular recording techniques. We shall examine the LRP of the isolated retina, development of X- and Y-cell properties, response of ganglion cells to moving stimuli, effect of masking of the receptive field surround on movement sensitivity, the effect of strabismus on ganglion cells, using surgically induced strabismic cats and Siamese cats with strabismus, responses of ganglion cells in kittens reared with lid-suture, and variations in response to temporally modulated stimuli in deprived kittens. 2.) Morphological studies on the size, shape and densities of the various retinal neurons, and on the appearance and spread of dendritic trees of known ganglion cell types through examination of Golgi-impregnated normal and deprived retinas will be done. An analysis of synaptogenesis in normal, deprived and strabismic cats will be done using ultrastructural techniques. The relationship of the LRP to differentiation of photoreceptor outer segments and density will be done in deprived kittens. 3) Studies on development of the optical system using frozen-sectioned eyes and laser-marking will provide us with accurate measurements of the posterior nodal distance in normal and deprived kitten eye. Wherever possible, specimens used for physiological experiments will be used in the analyses of morphology. Direct localization within the retina enables us to study the retinal field which corresponds with the visual field found in physiological studies. In this way cell components involved in neuronal pathways in the retina can be indirectly correlated with the physiological behavior of cells in the same part of the retina.